[][Add mt7981 sound node and update clock src]

[Description]
Add mt7981 sound node and update clock src

[Release-log]
N/A

Change-Id: I1299522161abec1da52b198dc71f843c7a18ecf9
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5455518
2 files changed